Skin Cancer in US Elders: Does Life Expectancy Play a Role in Treatment Decisions?

Abstract

Background

Non-melanoma Skin cancer, or Keratinocyte Carcinoma (KC) is the most common malignancy and the 5^th most costly cancer to Medicare. Several treatment types are effective, but treatments differ in cost and burden to patients. Because KCs do not typically affect survival, and most do not effect quality of life, we would expect lower frequency of intensive surgical treatments in patients with limited life expectancy.

Objectives

To examine whether life expectancy influences treatment pattern.

Design and Setting

We analyzed data from the nationally representative Health and Retirement Survey, linked to Medicare claims.

Participants

We included 9,653 treatments from N=2702 patients ≥65 years treated for either basal or squamous cell carcinoma between 1992 and 2012. Limited life expectancy defined by advanced age >85, medical comorbidities, Charlson score of ≥3, difficulty in at least one activity of daily living (ADL) and Lee index ≥13.

Measurements

Treatment type, including Mohs micrographic surgery (most intensive, highest cost), excision, or ED&C (least intensive, lowest cost) by procedure codes.

Results

Most KCs (61%) were treated surgically. Rates of Mohs (19%), excision (42%) and ED&C (39%) were no different in patients with limited life expectancy compared to those with normal life expectancy. For example, 19% of patients with difficulty or dependence in ADLs, 20% of patients with a Charlson score >3 and 15% of patients in their last year of life, received Mohs surgery. In addition, patients who ultimately died within 1 year of diagnosis were treated in the same way as those who lived longer.

Conclusion

Treatment for KC, a generally non-fatal condition, appears to be guided by a one-size-fits-all approach in which advanced age, health status, functional status, or prognosis are not associated with intensiveness of treatment. While intensive treatment for skin cancer may be indicated regardless of life expectancy when they cause symptoms, persons with limited life expectancy should be given choices, to ensure the treatment matches their goals and preferences.

INTRODUCTION

Keratinocyte carcinoma (KC) including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) is by far the most common cancer in the United States,(1) with over 3.5 million new cases treated each year.(2) A range of treatments that vary in invasiveness and cost can effectively treat most KCs. Common treatments include topical chemotherapy creams, tumor destruction with electrodessication and curettage (ED&C), or surgery. Surgery for KC can involve either simple excision, or Mohs micrographic surgery. The rationale for Mohs is that it aims to remove as much of the skin cancer as possible and prevent tumor recurrence, which for these typically slow-growing tumors occurs several years later (mean 3.3 years).(3) Although randomized trial data is limited, prospective cohort studies suggest that all surgical treatments offer >95% cure rates for primary tumors.(3)

When choosing among treatments with comparable clinical outcomes, considerations of cost, risks, procedure duration and patient preference matter. Mohs costs about twice as much as excision, which is about twice as expensive as ED&C.(4) Mohs also takes an average of 3 hours (up to 8 hours with repair), compared to an average of 1 hour for surgical excision or 20 minutes for ED&C.(5) Complications and patient-reported problems after these treatments are common, especially in elderly patients.(6) Medical problems with treatment including bleeding, pain and poor wound healing, are reported by 14% of patients,(6) and usually occur within the first year of treatment, while the potential benefit of more intensive treatment in preventing recurrence is several years in the future. This lag-time to benefit is an increasingly important consideration when making healthcare decisions in elderly individuals who may not live long enough to benefit from more intensive treatments, but may be at risk for short-term treatment related complications.(7, 8)

In some cases, KCs cause distress to patients, either because its location causes cosmetic concerns, or because it leads to symptoms. In these situations, even in patients with severe comorbidity, the most intensive treatment option is clearly appropriate if it is best treats KC related symptoms. However, previous research demonstrates that the large proportion of skin cancers cause no symptoms, and many are discovered incidentally. For the majority of skin cancer that causes no or minimal symptoms, a patient’s life expectancy should be a fundamental determinant of procedure choice in an older patients with skin cancer for two reasons a) patients with limited life expectancy often prefer more conservative treatment choices and b) patients with limited life expectancy may not live long enough to benefit from intensive treatments when there is significant time lag to benefit. Therefore, we would expect to see lower rates of Mohs surgery in patients at the end of life.

Although KC is the fifth most costly cancer for Medicare (over $500 million annually),(9, 10) only one single-city study has examined how prognostic characteristics of older patients impact treatment selection for this cancer.(11) We conducted this national study in order to examine whether patients with limited life expectancy were more likely to receive less invasive treatments. We took advantage of a national representative study linked to Medicare claims that had extensive information on patient characteristics that strongly impact life expectancy.

METHODS

Population

The Health and Retirement Study (HRS) is sponsored by the National Institute on Aging (grant number NIA U01AG009740) and is conducted by the University of Michigan. It is an ongoing nationally representative longitudinal study of the health of community-dwelling participants aged 50 and older that started in 1992. New participants are recruited to the study every six years in order to keep the study representative of US population. Interviews are administered over the telephone or in person every 2 years. Proxy respondents are asked to provide the answers for participants with physical or cognitive limitations. HRS collects information on financial, social, medical and functional status.

Our objective was to compare treatment patterns for KC according to individual prognostic characteristics in a nationally representative sample of older adults. Over 80% of HRS participants agree to have their Medicare claims linked to their HRS interviews.(12) Medicare claims data was available for years 1992 – 2008. Since the cancer treatments were ascertained from Medicare claims, our study is focused on participants 65 years or older who were eligible for Medicare and who had HRS data linked to Medicare claims data. We included subjects who had at least 1 year of Medicar1e claims data prior to the skin cancer claim..

Skin cancer treatment

The primary outcome was skin cancer treatment, defined based on both ICD-9 and procedure code. Skin cancer diagnosis was defined by ICD9 codes 232.xx or 173.xx. We looked at three different types of treatments: excision, ED&C and Mohs micrographic surgery. All procedures were identified in Outpatient and Carrier files using following HCPC procedure codes: Excisions (11600–11606, 11620–11626, 11640–11646, 26117, 11750); ED&C (17260–17266, 17270–17276, 17280–17286); Mohs micrographic surgery (17311, 17313, 17304).(13) Although radiation therapy for BCCs is becoming more common, this treatment modality was extremely rare in our study period, and not included.

We identified a total of 10739 Medicare claims that reported at least one potential skin cancer treatment. We excluded claims for which there was no ICD-9 diagnosis of skin cancer in the 90 days before the claim (n=1893, 17%) from the study. We excluded an additional 618 (6%) claims because there was no corresponding HRS interview within one wave before the claim. We limited our analysis to white participants (excluded N=164, 1.5% claims from non-white participants). Each patient could have multiple claims (because skin cancer patients tend to get multiple tumors) and each claim could have more than one treatment (e.g. two skin cancers removed at the same visit). Our final sample included 8064 Medicare claims for skin cancer treatment, corresponding to 9653 distinct treatments from 2702 individual patients (Figure 1).

Figure 1.

Study flow chart

Prognostic characteristics

We considered a number of variables for which there is strong evidence of a link to limited life expectancy in older patients:

1. Advanced age, defined as ≥ 85 years, which is associated with a life expectancy of 6 years.(14)

2. Comorbid disease burden, considering individual diagnoses (heart disease, stroke, cancer, lung disease, diabetes and hypertension identified by self report) and Charlson comorbidity score, an index of disease burden closely linked to survival(15). Charlson score was derived from Medicare claims data.

3. Self-reported independence in activities of daily living (ADLs, which include ability to bathe, dress, walk across a room, transfer in and out of bed, use the toilet, and eat). We classified subjects as having no difficulty in ADL function, having difficulty with one or more ADL, but able to do ADL without help, or needing help with at least one ADL (ADL dependence). This classification has been previously validated and strongly linked to survival.(16)

4. Lee Index score, a validated prognostic score combining information on age and comorbidities and function which is strongly linked to survival.(17) We classified subjects as having a score either above or below 13—a score of 13 is associated with 59% mortality at 4 years and 91% at 10 years. The prognostic indices used including the Charlson and Lee Index and ADL assessments have been extensively validated prognostic indices (14–17).

Statistical Analysis

We first performed descriptive analyses, summarizing the characteristics of our sample and the prevalence of the three treatments. Next, we did bivariate and multivariate analyses to examine the relationship between various prognostic characteristics and proportions of the 3 procedures included. Because surgery is more intensive than non-surgical treatments, we compared the rates of surgical procedures (excision and Mohs) and non-surgical procedures (ED&C). We also calculated differences between Mohs and non-Mohs procedures. Bivariate analyses used chi square tests. In order to directly estimate risk ratios instead of odds ratios, we used modified Poisson regression in multivariate analysis. (18) (19) All analyses were done at the skin cancer treatment level, but also accounted for clustering of treatments within individual patients. Our multivariate analyses used treatment choice as the outcome variable and the following predictor variables: age (<75, 75–85, ≥ 85), gender, income and net worth (dichotomized at median), comorbid conditions and functional status (not dependent in any, dependent in one, dependent in two or more). Analyses were performed using SAS 9.3 and Stata 12.1.

RESULTS

Table 1 shows the descriptive characteristics of the study participants (N=9653 claims from N=2702 patients). Most patients were older men (63% men, mean age 79 years) with sociodemographic and medical characteristics representative of this age group nationally. Nineteen percent of participants had some difficulty in at least one activity of daily living, 30% had a Charlson score of ≥3 and 14% had a Lee index of ≥13.

Table 1.

Characteristics of N= 2702 participants treated for skin cancer 1992–2008, N=9653 skin cancer treatments

Demographic Characteristics	% or mean (IQR)
Gender, Male	62.9%
Age, years	79.2 (range 65–106)
Income, $1000s	37 (22–66)
Wealth, $1000s	330 (127–775)
Comorbid diseases
Hypertension	57.4%
Diabetes	14.8%
Lung Disease	9.2%
Cancer (except skin)	24.9%
Stroke	12.6%
Heart Disease	36.6%
Activities of Daily Living (ADL)
No Difficulty in any ADLs	80.6%
Difficulty in at least one ADL	12.6%
Dependent in at least one ADL	6.8%
Dressing
No Difficulty	90.5%
Difficulty	5.3%
Dependent	4.2%
Eating
No Difficulty	96.6%
Difficulty	1.5%
Dependent	1.9%
Bathing
No Difficulty	93.4%
Difficulty	2.8%
Dependent	3.8%
Using toilet
No Difficulty	93.5%
Difficulty	4.9%
Dependent	1.6%
Walking Across Room
No Difficulty	92.2%
Difficulty	5.0%
Dependent	2.8%
Transferring in/out of bed
No Difficulty	95.0%
Difficulty	2.9%
Dependent	2.1%
Prognostic indices
Charlson(15)
<3	70.1%
≥3	29.9%
Lee Index(17)
<13	85.6%
≥13	14.4%

Table 2 shows the proportion of patients in the sample treated with each of the 3 most common procedures. Overall 61% of tumors underwent surgery: 19% underwent Mohs surgery and 42% underwent excision. The remaining 39% were treated with ED&C. No significant difference was noted in treatment rates in groups divided according to patient advanced age, medical comorbidities, indicators of limited life expectancy, or difficulty or dependence in activities of daily living. Among patients who ultimately died within 1 year of treatment, 15% received Mohs surgery (compared to 17% among those who lived longer p=0.34 ) and 51% received excision (compared to 43% of those who lived longer p=0.06).

Table 2.

Proportion of patients treated with each of the 3 most common procedures

	N	Mohs	Excision	ED&C	p-value1
OVERALL	9653	1796	4066	3791
Age
<75	2979	18.9%	43.1%	38.0%	0.34
75–85	4403	17.4%	41.7%	40.9%
≥ 85	2271	20.6%	41.7%	37.7%
Last year of life
No	8051	17.2%	42.9%	39.9%	0.34
Yes	451	14.9%	51.2%	33.9%
Comorbidities
Hypertension
No	4110	18.3%	42.7%	39.0%	0.81
Yes	5540	18.8%	41.7%	39.5%
Diabetes
No	8219	18.1%	42.0%	40.0%	0.07
Yes	1432	21.7%	43.0%	35.3%
Lung Disease
No	8763	18.4%	42.1%	39.5%	0.32
Yes	888	20.9%	42.0%	37.0%
Cancer (except skin)
No	7234	18.0%	42.5%	39.5%	0.15
Yes	2400	20.5%	41.2%	38.3%
Stroke
No	8435	18.4%	42.6%	39.0%	0.50
Yes	1214	20.0%	38.6%	41.4%
Heart Disease
No	6116	17.8%	43.8%	38.4%	0.20
Yes	3532	20.1%	39.2%	40.7%
Prognostic Indices
Lee Index
<13	8266	18.6%	41.9%	39.5%	0.93
≥13	1387	26.0%	43.3%	37.9%
Charlson
<3	6764	17.7%	42.0%	40.3%	0.08
≥3	2889	20.6%	42.5%	36.9%
Activities of Daily Living
Summary
No Difficulty	7778	18.6%	42.6%	38.8%	0.90
Difficulty/dependent	1859	18.8%	39.9%	41.3%
Bathing
No Difficulty	8989	18.7%	42.0%	39.3%	0.44
Difficulty/dependent	640	16.9%	43.3%	39.8%
Dressing
No Difficulty	8713	18.3%	42.3%	39.4%	0.33
Difficulty/dependent	916	21.1%	40.4%	38.5%
Eating
No Difficulty	9296	18.7%	42.2%	39.1%	0.45
Difficulty/dependent	332	16.3%	38.9%	44.9%
Transferring in/out of bed
No Difficulty	9149	18.5%	42.2%	39.3%	0.253
Difficulty/dependent	482	21.6%	39.0%	39.4%
Using toilet
No Difficulty	8968	18.8%	42.4%	38.8%	0.41
Difficulty/dependent	628	16.6%	36.6%	46.8%
Walking across room
No Difficulty	8873	18.6%	42.1%	39.3%	0.93
Difficulty/dependent	751	18.9%	41.0%	40.1%

¹P value for comparison of those that received Mohs treatment and those that did not receive Mohs treatment.

The multivariate relative risk (RR) of receiving Mohs comparing patients with and without limited life expectancy, did not differ from 1, even after adjusting for age, gender, socioeconomic status, medical comorbidities and ability to perform activities of daily living (Supplementary Table 3).

DISCUSSION

Choice of treatment for basal and squamous cell skin cancer should be influenced, at least in part, by patient life expectancy because KC is a non-fatal disease where the risks of intensive treatment may outweigh the benefits in some patients who have few years to live. In this nationally representative study of older Americans, we found that choices among types of KC treatments were not influenced by individual prognostic characteristics. In particular, patient life expectancy whether measured by advanced age, severe medical comorbidities or impaired functional status, does not seem to influence treatment choice, including the rates of Mohs surgery. We noted similar rates of Mohs surgery and higher rates of excision in patients who ultimately died within 1 year of treatment compared to those who lived longer. Together, these findings suggest that currently skin cancer treatment choice may not be tailored to the life expectancy and functional status of individual patients.

These findings build on our prior single-city study showing that treatment choice was not influenced by patient life expectancy even after adjusting for tumor characteristics (histology, location, degree of invasiveness). In our prior study, we found that most patients are not often bothered by their tumors (72%),(6) fewer than 5% of these tumors recur regardless of treatment type(3) and many patients die of unrelated causes within 5 years (43%), while no patients died of KC.(6) Meanwhile, a significant proportion of patients report a problem after treatment procedures (27%).(6)

We acknowledge that there are selected circumstances in which a KC should be treated aggressively, even in patients with limited life expectancy. In some cases, a KC can cause cosmetic distress or symptoms or ulcerate. Even is such a KC does not impact life expectancy, whichever treatment best treats the symptoms is indicated. Our claims data did not have information on symptoms, and therefore, some of the Moh’s resections may have been indicated, even in those with limited life expectancy. However, prior research demonstrates that the majority of KCs cause no symptoms, and in this case, treatments that are the least burdensome to the patient should be given special consideration.

A major limitation of this study is that we only included skin cancers that were treated by a procedure; since our sample was defined by Medicare procedure codes. Therefore untreated tumors, and tumors treated by topical therapies (e.g. Imiquimod) or radiotherapy are not included. Because our dataset did not include untreated tumors, these findings pertain to decision making after a decision to treat a tumor—they do not deal with the decision to treat itself. However, based on other studies, the proportion of untreated tumors in the US is likely very small (20) (11)and imiquimod and radiotherapy were very rare modes of treatment in the years studied. While we show that limited life expectancy is not associated with treatment decisions, a limitation of this study is that we could not assess whether the treatments offered were appropriate. It is possible invasive procedures were appropriate, even at the end of life, because they were used on medically dangerous or symptomatic tumors. We did not have information on many factors that may have influenced treatment choices including tumor histology, location or size. We also did not have information on patient preferences, and it is possible that some elderly patients would have requested more intensive treatment options for their BCCs. Furthermore, we only evaluated procedures for KC and not the more recent topical treatments including Imiquimod and 5-fluorouracil. Our KC selection criteria relied on procedure codes, and therefore would not capture untreated tumors, although we expect this is a very small proportion of KCs.(11) We also did not have information on the specialties of physicians treating these tumors.

Despite these limitations, the main advantage of this study is that it includes nationally representative data spanning 16 years. Taken together with our prior cohort study, which did include detailed information on tumor and individual patient characteristics(11) including bother we likely have an accurate picture of US patterns of skin cancer treatment in patients with differing life expectancies. Determining appropriate care of non-fatal conditions for patients with limited life expectancy is challenging.(21) For example, rates of prostate cancer screening in patients with limited life expectancy are probably excessive, given the known risks of screening and limited benefits of treatment.(22, 23) Similarly, a significant proportion of patients with metastatic cancer receive routine screening tests that are unlikely to provide any benefit.(24) A study of Medicare beneficiaries showed that over 30% of patients underwent surgery in the last year of life.(25) Our study adds to the growing argument for prudent use of procedures toward the end of life.

Conclusion

In conclusion, choice of treatment for basal and squamous cell skin cancer is unaffected by many patient characteristics including advanced age, functional status, medical comorbidities or patient life expectancy. A more individualized approach to skin cancer treatment may be preferred and provide more optimal care for frail elderly patients. Although it is impossible to predict any individual’s precise life expectancy, and advanced age alone should not dictate or restrict treatment options as life expectancy varies tremendously among those of similar age, it is possible that some patients would chose less invasive treatments if they were given all relevant information. It is also possible that physicians would make different recommendations if they had more guidance (including decision tools or evidence based guidelines) on this topic. We hope that this study will add to the debate about optimal treatment decisions at the end of life.